A photo posted on the Mutianyu Great Wall's official WeChat account shows two foreigners climbing over the Great Wall on April 30.

Two Senegalese tourists were blacklisted for having crossed over an undeveloped part of the Great Wall on April 30 in Huairou District, Beijing, Beijing Daily reported today.

Other tourists discovered and reported the two after witnessing them climbing on the wall despite a sign that says "No crossing" at the No. 20 defending tower of the Mutianyu Great Wall.

The office at Mutianyu Great Wall scenic area tracked down information on the two Senegalese through a ticketing and monitoring system after receiving the report. They are prohibited from buying tickets to the Great Wall in the future.

The area outside the No. 20 defending tower is closed to the public. Many walls have collapsed and others are riddled with loose bricks. Climbing on the undeveloped part of the Great Wall is not only dangerous, but also damages its historical appearance, according to the report.